{"id":"F2007L01447","name":"AD/ECUREUIL/126 - Fuselage Centre Cross-Member under Cabin Floor","slug":"ad-ecureuil-126-fuselage-centre-cross-member-under-cabin-floor","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65851,"registerId":"commonwealth-F2007L01447-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Eurocopter AS 350 (Ecureuil) Series Heli","sectionType":"division","heading":"Eurocopter AS 350 (Ecureuil) Series Helicopters","content":"### Eurocopter AS 350 (Ecureuil) Series Helicopters\n\n| AD/ECUREUIL/126 | Fuselage Centre Cross-Memberunder Cabin Floor | 7/2007 TX |\n| --------------- | --------------------------------------------- | --------- |\n\n| Applicability: | Model AS350 B, BA, BB, B1, B2, B3 and D helicopters, all serial numbers, delivered before 1 January 2007, and equipped with collective-to-yaw control coupling with or without an Automatic Flight Control System.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Confirm installation of the cross-member at station X 2165 and of the doublers at stations X 2325 and Y 269 as detailed in the Accomplishment Instructions paragraph of Eurocopter Alert Service Bulletin (ASB) 53.00.37 original issue, or later EASA approved revision.If the cross-member and the doublers are installed, no further action is required.2. If the cross-member and/or doublers are not installed, check for cracks by a visual or a dye penetrant inspection, the centre cross-member at station X 2325, in the area around the attachment point of the tail rotor directional ball-type control as detailed in the Accomplishment Instructions paragraph of ASB 53.00.37 original issue, or later EASA approved revision.If no cracking is detected:Before further flight, check the tail rotor control rigging in accordance with the Accomplishment Instructions paragraph of ASB 53.00.37 original issue, or later EASA approved revision.Repeat the Requirement 2 inspection until Requirement 3 is accomplished.If any crack is detected:Flight is prohibited.3. Install the cross-member at station X 2165 and the doublers at stations X 2325 and Y 269, in accordance with the Appendix paragraph of ASB 53.00.37 original issue, or later EASA approved revision.Note: EASA Emergency AD 2007-0139-E refers. |\n\n| Compliance: | For Requirements 1 and 2: Within 10 flight hours or 1 month after 18 May 2007, whichever occurs first. Repeat the Requirement 2 inspection at intervals not to exceed 55 flight hours; until accomplishment of Requirement 3.Requirement 3: Within 12 months after 18 May 2007.                                                                                                                                                                                                                                                                                                                                  |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 18 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n| Background: | The EASA received a report of a crack in the area of the centre cross-member at station X 2325, at the attachment point of the yaw channel ball-type control sheath stop of a Model AS 355 N helicopter fitted with the collective-to-yaw control coupling. Investigation revealed that the helicopter was not equipped with the structure doublers, which are combined with the collective-to-yaw control coupling installation. Repetitive overloads on the non-modified cross member will cause it to crack, and result in reduction of yaw control travel with consequent reduced yaw control for the pilot. |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n16 May 2007","sortOrder":0},{"sectionNumber":"AD/ECUREUIL/126","sectionType":"part","heading":"AD/ECUREUIL/126","content":"## AD/ECUREUIL/126","sortOrder":1},{"sectionNumber":"Fuselage Centre Cross-Memberunder Cabin ","sectionType":"part","heading":"Fuselage Centre Cross-Memberunder Cabin Floor","content":"## Fuselage Centre Cross-Member  \nunder Cabin Floor","sortOrder":2},{"sectionNumber":"7/2007 TX","sectionType":"part","heading":"7/2007 TX","content":"## 7/2007 TX","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive remains narrowly focused on the original airworthiness problem: potential cracking of the centre cross‑member where the tail‑rotor control attaches in helicopters that lack the reinforcing doublers associated with the collective‑to‑yaw coupling. It does not broaden regulatory reach beyond inspecting and requiring installation of the specified structural reinforcement and associated inspections."},"complexity_factors":["Single, focused safety issue (centre cross‑member and doublers) affecting a defined set of models/serials","Three discrete requirements (confirm installation; recurring inspection if not installed; mandatory installation within 12 months)","A small number of compliance timeframes (10 flight hours or 1 month; repeat every ≤55 flight hours; install within 12 months)","Cross‑reference dependency on Eurocopter ASB 53.00.37 (original issue) or later EASA‑approved revision for procedural detail","Two inspection methods permitted (visual or dye‑penetrant), and a simple fail condition (any crack = flight prohibited)","Limited number of affected stations (X 2165, X 2325, Y 269) referenced"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an airworthiness directive (safety order) that applies to Eurocopter AS350 (Ecureuil) models B, BA, BB, B1, B2, B3 and D, for all serial numbers delivered before 1 January 2007, when those helicopters are fitted with a collective‑to‑yaw control coupling (the mechanical link between the collective pitch lever and tail‑rotor/yaw control) — whether or not they also have an Automatic Flight Control System (AFCS).\n\n- It requires three possible actions, depending on the helicopter's current configuration:\n  - Requirement 1: Confirm whether a centre cross‑member (a structural beam under the cabin floor at station X 2165) and reinforcing plates called \"doublers\" at stations X 2325 and Y 269 are already installed, using the procedures in Eurocopter Alert Service Bulletin (ASB) 53.00.37 (original issue) or a later EASA‑approved revision. If those parts are installed, nothing more is required.\n  - Requirement 2: If the cross‑member and/or doublers are NOT installed, perform inspections (visual or dye‑penetrant) of the centre cross‑member area around the tail‑rotor control attachment at station X 2325 to look for cracks. If no crack is found, inspect the tail‑rotor control rigging before further flight and repeat the crack inspection at intervals not to exceed 55 flight hours until the parts are installed. If any crack is found, flight is prohibited (the helicopter must not be flown).\n  - Requirement 3: If the parts were not previously installed, install the centre cross‑member at X 2165 and the doublers at X 2325 and Y 269 in accordance with the ASB (or later EASA‑approved revision).\n\n- Compliance deadlines set by the directive:\n  - For Requirement 1 and the initial Requirement 2 inspection: within 10 flight hours or 1 month after 18 May 2007, whichever occurs first.\n  - Repeat Requirement 2 inspections at intervals not exceeding 55 flight hours until Requirement 3 is completed.\n  - Requirement 3 (installation of parts): within 12 months after 18 May 2007.\n\n- The directive references an EASA Emergency AD (2007‑0139‑E) and the manufacturer’s ASB for detailed instructions.\n\n**Who it affects**\n\n- Operators and maintenance organisations responsible for AS350 helicopters delivered before 1 Jan 2007 that have the collective‑to‑yaw coupling. Owners/operators of affected helicopters must carry out the checks, inspections, and part installations required by the AD. Maintenance providers will perform the inspections/repairs and supply parts and labour.\n\n**Why it matters (stated purpose and mechanical risk)**\n\n- The stated reason is that EASA received a report of a crack in the centre cross‑member area where the tail‑rotor directional ball‑type control attaches. That helicopter lacked the reinforcing doublers that accompany the collective‑to‑yaw coupling installation. Repeated overloads on an unreinforced cross‑member can lead to cracking, which can reduce available yaw control travel for the pilot — a condition that could impair safe control of the helicopter.\n\n**Practical consequences, costs and implementation considerations**\n\n- Who pays: Operators bear the direct costs — inspections (labour), dye‑penetrant materials if used, potential grounding time, and the cost and labour of installing the cross‑member and doublers if required.\n\n- Who decides and enforces: The operator must confirm configuration and schedule inspections/installation in compliance with the AD. A civil aviation authority enforces compliance; maintenance must follow the Eurocopter ASB or an EASA‑approved revision.\n\n- Behaviour changes required: Operators must (a) inspect configuration, (b) perform recurring crack inspections until reinforcement is fitted, and (c) install reinforcement within 12 months if not already present. If a crack is found, operations must cease until repair/installation is done.\n\n- Compliance burden and implementation risk: The AD cross‑references the manufacturer’s ASB and requires EASA‑approved revisions for the detailed procedures — this creates dependence on the ASB for exact methods. Availability of parts and qualified maintenance slots can cause aircraft downtime. Dye‑penetrant inspection effectiveness depends on access and technique; small or hidden cracks might be missed, creating an implementation risk until the strengthening hardware is fitted. Finding a crack leads to immediate grounding, which concentrates operational disruption on the affected operator.\n\n- Market and private enterprise effects: The requirement does not change fundamental operating rules or market access; it imposes a retrofit/inspection cost on operators of affected helicopters. Those operators face potential short‑term loss of availability; maintenance providers receive work to perform the inspections/retrofits.\n\n- Concentrated benefits and costs: The safety benefit (reduced risk of control‑loss from a cracked cross‑member) accrues to all operators and occupants; the direct costs are concentrated on operators of the affected helicopters (delivered before 1 Jan 2007). There is no new subsidy or compensation mechanism in the AD.\n\n- Substitution and unintended effects: Some operators may take affected helicopters out of service pending installation, leading to short‑term capacity loss. If parts or qualified installers are scarce, scheduling delays could extend the period during which repetitive inspections are required.\n\n**Bottom line**\n\n- The AD sets a clear safety action: confirm whether reinforcement is installed; if not, inspect repeatedly for cracks and fit the reinforcement within a year. It mandates grounding if a crack is found. Operators pay for compliance and must manage inspection cadence and any retrofit downtime. The AD’s stated safety justification is a reported crack that could reduce yaw control — the AD addresses this by mandating inspection and structural reinforcement per the manufacturer’s ASB."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific structural failure mode in a defined subset of AS 350 helicopters. The document remains focused on the single safety issue of cross-member cracking and does not expand into unrelated systems or aircraft types."},"complexity_factors":["Multiple conditional pathways (if installed → stop; if not installed → inspect; if cracked → ground aircraft; if not cracked → repeat inspection)","Technical aviation terminology requiring specialised knowledge (station X 2165, doublers, dye penetrant inspection, collective-to-yaw coupling)","Cross-reference to external technical document (Eurocopter Alert Service Bulletin 53.00.37) for actual implementation details","Dual compliance timelines (10 flight hours OR 1 month for initial action; 55 flight hour intervals for repeats; 12 months for final action)","Specific applicability criteria combining model variants, serial numbers, delivery dates, and equipment configurations"],"plain_english_summary":"This mandatory CASA Airworthiness Directive requires owners/operators of Eurocopter AS350 B/BA/BB/B1/B2/B3 and D helicopters delivered before 1 Jan 2007 and fitted with collective-to-yaw coupling to inspect and, if necessary, install a reinforcement on the centre cross-member under the cabin floor that anchors the tail-rotor control.\n\nIt prevents fatigue cracking that can reduce tail-rotor authority and lead to loss of yaw control; inspections and eventual reinforcement are compulsory within the AD’s compliance timeframe."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-126-fuselage-centre-cross-member-under-cabin-floor","history":"/api/acts/ad-ecureuil-126-fuselage-centre-cross-member-under-cabin-floor/history","analysis":"/api/acts/ad-ecureuil-126-fuselage-centre-cross-member-under-cabin-floor/analysis","conflicts":"/api/acts/ad-ecureuil-126-fuselage-centre-cross-member-under-cabin-floor/conflicts","importantCases":"/api/acts/ad-ecureuil-126-fuselage-centre-cross-member-under-cabin-floor/important-cases","documents":"/api/acts/ad-ecureuil-126-fuselage-centre-cross-member-under-cabin-floor/documents"}}